The ability of an insect to respond to chemical stimuli is necessary for the insect to reproduce, mate, and feed. For example, insects respond to certain chemical stimuli by moving up a chemical gradient to identify and target a host. Mosquitoes, in particular, are believed to use olfaction to identify and target sources of bloodmeal for reproductive purposes. This behavior contributes to the spread of diseases in humans, such as malaria, encephalitis, and dengue fever; as well as, animal and livestock disease.
Olfaction plays a critical role in insect behaviors among agricultural pests and disease vectors. Hildebrand, et al., 1997, Annu. Rev. Neurosci, 20:595–631. In Drosophila melanogaster (the common fruit fly), the olfactory system functions through a rapid cycling between an on and off state of certain regulatory molecules. The olfactory signal transduction cascade is “turned on” by ligand-based activation of an odorant receptor and transduction of the signal by G-protein coupled second messenger pathways Boekhoff et al., 1994, J. Neurosci, 14:3304–9. The “on signal” is rapidly and substantially terminated in the Drosophila system through the modification of the odorant receptor such that the G-protein coupled second messenger pathway is deactivated. Dohlman et al., 1991, Annual Review of Biochemistry, 60:653–88. Olfactory transduction is provided by second messenger pathways of G protein-coupled receptors. Reed, R., 1992, Neuron 8:205–209; Bloekhoff, et al, 1994, Neurosci 14:3304–3309.
The structural and functional characteristics of the mosquito olfactory system has not been characterized to date. Given the importance of the controlling this pest and disease vector, what is needed is the identification and characterization of the genes and polypeptides that function for mosquito olfaction and methods of use thereof for mosquito management.